Many vasocclusive events, such as heart attacks and strokes, are caused by plaque build-ups in arteries. As one specific example, atherosclerotic plaque is known to build-up in the walls of arteries in the human body. Such plaque build-up restricts circulation and often causes cardiovascular problems, especially when the build-up occurs in coronary arteries.
One common method for opening partially occluded body internal passages is to guide a medical device to the diseased site, where it is used to carry out the needed treatment. A guidewire is usually used for advancing a catheter device thereover via body internal passages towards the treatment site. Typically, the distal tip of the guidewire is introduced into the body of the treated subject via an incision and advanced therethrough towards the treatment site, thereby forming a path leading to the occluded site through said body internal passages. The catheter, or any other suitable treatment devices (e.g., balloon catheter, stent or rotational atherectomy device), may be then threaded over the guidewire and advanced through said internal passages using the guidewire as a rail.
Total or near-total occlusions in body internal passages can, partially or entirely, block the passage therethrough. For example, in patients who suffer from coronary CTO (chronic total occlusion), the successful performance of a Percutaneous Transluminal Coronary Angioplasty (PTCA) is a technical challenge. The factor that is most determinative of whether the practitioner can successfully perform PTCA on patients suffering from coronary CTO is his ability (or inability) to advance a suitable guidewire from a position proximal of the lesion to a position distal of the lesion while remaining inside the true vessel lumen (without performing perforation or dissection of the artery wall).
In some instances, such as where the occlusive matter is soft or where the body internal passage is partially occluded, the guidewire can easily be pushed through the occlusive matter itself, thereby allowing the guidewire to remain within the body internal passage. However, in other cases, such as when the body internal passage is totally occluded by hard plaque (e.g., calcified atherosclerotic plaque), the guidewire cannot cross the occlusion and may deviate to the side and penetrate through layers of the passage walls (e.g., the intima—inner layer of a vessel wall), thereby creating a neo-lumen therethrough (e.g., through the sub-intimal space—within the wall of the artery between the intima and media, or adventitia, i.e. a dissection), or even completely exit said internal passage, i.e. a perforation.
Several techniques are known for passing through an occluded internal passage, such as laser catheters (U.S. Pat. No. 6,673,064), ultra sonic catheters (U.S. Pat. No. 6,702,748), and tissue displacement or hinged expansion devices (U.S. Pat. No. 6,800,085). In all of those techniques the occlusion is opened by means of a catheter device equipped with operative means for occlusions opening. However, the prior art devices suffer from lack of flexibility and maneuverability due to the bulky structure of their catheter devices. Consequently, the treatment procedures which utilize these prior art devices are substantially different from conventional catheterization procedure workflow as commonly practiced in regular cases (non CTO cases).
The aforementioned prior art solutions also suffer from lack of ability to indicate to the practitioner in real time, i.e. while carrying out the procedure, whether he is navigating the treatment devices through the occlusion (true lumen) or if he is actually perforating or dissecting the body internal passage, e.g. the artery.
Other known procedures, such as described in U.S. Pat. No. 6,852,109, propose a method for forming a passage through the CTO by a guidewire having active Radio Frequency (RF) ablation tip, with Optical Coherence Reflectometry (OCR) capability for sensing the position of the tip. However this known type of guidewire is a special guidewire comprising a mechanism for transferring RF energy and a following catheter with fiber optics for the OCR capability. These restraints are relatively rigid and therefore diminish the flexibility of the device, which is an important feature for carrying out in vivo navigation. Thus, also this prior art device suffers from lack of flexibility, and the need to deviate from the conventional practice workflow of the practitioner.
Another solution used for determining whether an organic tissue is healthy or not is using IVUS (intravascular ultrasound), for example as described in U.S. Pat. Nos. 6,685,644 and 6,685,643, however lack of data due to poor transmission in this known method and calcified build-ups that cause “acoustic shadowing” yield poor results in determining tissue type and true lumen detection.
In still another solution used such as described in U.S. Pat. No. 5,908,395, a hand held vibrator is attached to the proximal side of a guide wire, or a catheter through which the guidewire is threaded.
The guidewire then conveys the proximal vibrations to its distal end, subject to the specific passage of the guidewire through the arteries. If indeed these vibrations reach the distal end of the guidewire they may be efficient in penetrating and recanalization of CTOs (chronical total occlusions). However, there is a problem in that the vibrations may be absorbed before reaching the distal end. In addition, using an external hand held vibrator interferes with the standard operation of the guidewire, and limits the operator from conveniently controlling the guidewire by manually holding its proximal end, again causing the need to deviate from the conventional practice workflow of the practitioner.
There thus exists a need for devices and techniques for treating occluded body internal passages, for characterizing the tissue/substance the treatment device is in contact with and determining its location within and about the body internal passage, and for safely opening occlusions therein without damaging the occluded internal passage.
It is therefore an object of the present invention to provide a method and device for opening occluded body internal passages and/or body organs.
It is another object of the present invention to provide a method and device for safely navigating treatment means, such as a catheter device, to a treatment site through body internal passages.
It is a further object of the present invention to provide a method and device for in vivo characterizing the tissue and/or substance being in contact with a treatment device.
It is yet another object of the present invention to provide a catheter device capable of inducing vibrations in a guidewire contained therein.
In still another solution used as described in copending application PCT/IL2006/000541, a device comprises a magnetic guidewire housed in a coiled catheter. The guidewire is vibrated by feeding electrical current via the coils of the catheter, thus providing magnetic excitation of the guidewire tip. However, because of the magnetic guidewire structure and dimensions this solution may not be optimized to match the physician procedure. The magnets beads added to the guidewire may increase the diameter thereof, and may thusprevent the use of some devices that are threaded onto regular guidewires.
More particularly, these over-the-wire devices sometimes have a lumen that is only marginally larger in diameter than the diameter of the guidewire. By adding magnets to the guidewire, these over-the-wire devices may not suited to be threaded onto the magnetic guidewire, as the diameter of the magnets may be bigger than the inner diameter of the lumen of the catheter.
In still another solution used such as described in WO 00100252, a catheter or guidewire that is made from ferromagnetic means and is positioned such that a predetermined portion of the device lies adjacent to the target site. A magnetic field source that changes over time in magnitude and/or direction, of sufficient strength is disposed outside the patient's body in sufficient proximity to the intrabody device to induce motion in the device through the oscillating magnetic field that it emits. However this method significantly deviates from the physician regular workflow and requires the change of the catheterization lab in order to facilitate the magnet field exterior device, furthermore, it is almost impossible to guarantee that the magnetic member that lies within the body cavity will be exactly adjusted to the magnetic source.
In still another solution such as described in WO 94/12234, a flexible elongate device having a distal extremity with a vibratory impact tip embedded with a coil spring piston like mechanism for catheters and guide wires. However, because of the fact the guidewire or catheter are embedded with a spring coil vibrational mechanism, the mechanical properties of the guidewire and the catheter significantly change and the ability to pass over the wire devices is reduced, thus deviating from the standard workflow of the procedure.
Several uses of magnetic coupling of guidewires are known, such as in U.S. Pat. No. 5,813,996, however this known coupling is static and is used as a guide wire extension system including a guide wire and an extension wire and means for magnetically coupling the guide wire to the extension wire, and not as a means for magnetic vibration for gateway passage opening.
There thus exists a need for devices and techniques for treating occluded body internal passages, for characterizing the tissue/substance the treatment device is in contact with, for determining its location within and about the body internal passage, and for safely opening occlusions therein without damaging the occluded internal passage, while keeping the same work flow (clinical procedure), and enabling the physician to use exactly the same over-the-wire devices.
Further more, guidewires are a great technical and clinical challenge. The structure of the guidewire, and generally speaking composition of materials and dimensions of the different segments of the guidewire set the guidewire's characteristics. More specifically, most guidewires are constructed such that their distal portions (typically the distal 100-300 mm of the guidewire) are made of a specially shaped and tapered core, wrapped with a special spring-like coil. This coil, together with the inner shaped core of the guidewire influences dramatically the behavior and characteristics of the guidewire.
Therefore, it is desirable to be able to make use of the existing structure of conventional guidewires, and thus maintaining the critical mechanical characteristics of the guidewire, while adding the capability to generate an alternating magnetic field.
This alternating magnetic field can then serve to generate alternating magnetic forces that oscillate the tip of the guidewire providing it with active drilling capabilities to open occlusions.
It is an object of the present invention to provide a method and device for opening occluded body internal passages and or body organs, by providing additional means and implementing the coils already embedded into a guidewire in such a way so as to enable electrical generation of alternating magnetic fields.
Other objects and advantages of the invention will become apparent as the description proceeds.